Copying paper



Patented F ch. 7, 1939 PATENT OFFICE COPYING PAPER Maximilian Paul Schmidt, Wiesbadcn Biebrich,

Germany, assignor to Kalle & (10., Aktiengesellschaft, Wiesbaden-Biebrich, Germany No Drawing.

Application December 8,

Serial No. 178,658. In Germany April 3, 1936 7 Claims.

The present invention relates to copying paper.

It is known to employ in typing, copying paper which is coated on both sides with a dark transfer composition. With the employment of this 5 paper documents are obtained which are written upon on the rear side as well and which, in consequence of this, are particularly suitable for duplication by the photographic copying processes. The writing on the rear side is, it is true,

0 sometimesconsidered to be unusual and disturbing and it exhibits also the disadvantage that when a number of sheets of this kind are laid one upon the other, smearing may occur.

An object of the invention is an improved l5 copying paper not exhibiting the said disadvantages. Another object of the invention is a method of using the new copying paper. Further objects of the invention will be seen from the following description.

It has been found that a practically valuable copying paper is obtained if a paper is prepared on the one side in the normal manner with a dark dyestufi which is mixed as usual with waxes, fats and other customary materials, while to the '5 other side of the paper a similarly constituted layer is applied which, however, instead of the dark dyestuff, contains a lighter material which absorbs chemically operative light, particularly ultraviolet light.

It is advantageous if the last-mentioned material is visible only to as small an extent as possible or not at all. During the writing operation the new copying paper is'so placed that the lighter layer comes into contact with the rear side of the paper which is to be written upon. on the said rear side light writing is then ob-, tained, which is not disturbing or hardly disturbing, and in spite of this very much facilitates the duplication of the document by the photographic copying process. Moreover any rubbing off of the rear side layer which may occur when several of such written sheets are placed one upon the other is not noticeable or only slightly noticeable.

u A copying paper according to theinvention is obtained for example if a tissue paper is'provided in the customary manner on the one side with a layer which in addition to fats, waxes and other customary additions contains nigrosine,

. while to the other side a layer is applied which.

instead of nigroslne contains chrysoidine.

Instead of the chrysoidine it is possible to use for example 3-methyl-4-amino-2 -methyl-azobenzene, the umbelliferone carboxylic acid salt of sodium, the sodium salt of 4.4'di-(p-dimethylaminobenzoylamino) diphenyl 2.2'-disu1phonic acid, 4-dimethylamino-1.1'benzophenone and other similar compounds.

The following examples illustrate the invention: (1) 3 kgs. technical stearic acid, 500 grams 4.4'-di-(dimethylamino)-benzophenone and .1 of a kg, of pressed tallow are melted together hot and applied in the customary manner to the unprepared side of an ordinary copying (carbon) paper. Instead of the said ketone, naphthostyrile or ecridone may also be employed.

(2) 1 part by weight of 4-dimethylamino-1.1- benzophenone is melted up with 25 parts by weight of stearine on the water bath. 25 parts by weight of parafiin are then added and the mass is applied to the rear side of an ordinary carbon paper.

(3) 4 parts by weight of naphthostyrile are dissolved on the water bath in 100 parts by weight of stearine. This solution is worked up, if desired after the addition of wax, paraffin, ceresine or similar substances, according to Example 2.

(4) The procedure is as in Example 2, but instead of the 4-dimethylamino-1.1'-benzophenone mentioned in that example m-toIyI-LZ-pseudoazimido-5-naphthol is employed.

I claim:

1. A carbon paper having on its one surface a layer consisting of a dark transfer composition and on its other surface a layer consisting of a considerably lighter transfer composition comprising a substance which absorbs ultra-violet light but is stable to light.

2. A transfer sheet coated on its one surface a with a layer comprising in admixture a waxy substance and a dark dyestuif and coated on its other surface with a layer comprising in admixture a Waxy substance and a substantially colorless substance which absorbs ultra-violet light without decomposing.

3. A carbon paper according to claim 1, wherein the said lighter transfer composition is substantially colorless.

4. A transfer paper having on its one side a layer comprising in admixture a waxy substance and a black dyestuff and on its other side a layer comprising a waxy substance and 4.4'-di-(dimethylamino) -benzophenone.

5. A transferpaper having on its one side a '50 layer comprising in admixture a waxy substance and a black dyestuif and on its other side a layer comprising a waxy substance and 4-dimethylamino-1.1-benzophenone, Y

6. A transfer paper having on its one side a layer comprising in admixture a waxy substance and a black dyestufl and on its other side a layer comprising a waxy substance and naphthostyrile.

'7. The process which consists in arranging a carbon paper having on its one surface a layer consisting of a. dark transfer composition and on its other surface a layer consisting of a considerably lighter transfer composition comprising a substance which absorbs ultra-violet light without decomposing between two pieces of paper and writing on the paper contacting with the surface of the carbon paper having the said 5 lighter transfer composition.

' PAUL'scmmim 

